Intel Inboard 386

Intel Inboard 386/AT and Intel Inboard 386/PC were 1980s ISA boards which allowed to upgrade respectively an IBM AT or an IBM PC computer into Intel 80386 machines.

The board was a full length ISA expansion card that came with a 386 processor (16 MHz), an 80387 math coprocessor socket and 1 MB of RAM. 2MB and 4MB memory expansion options were also available. The board was activated after the regular XT/AT BIOS had finished its POST (Power-on self test) routines and the OS had loaded the Intel DOS based .sys device drivers (from config.sys).

Some of the disadvantages of the product were:

1) Though the 80386 supported a 16 bit ISA bus, if you plugged the Inboard into an XT, you were limited to 8 bit ISA expansion cards.

2) If your BIOS did a slow POST, you would still have to wait for a painfully long length of time before the RAM checked out ok and you could begin to use the 80386 features. The Inboard did not "override" the on-board motherboard BIOS/firmware.

Other than that, you could actually run applications that just wouldn't run on an XT. Some of the apps that were verified by Wikipedia contributors included:

1) Ventura 2.0 Desktop Publishing Software (with Hercules monochrome graphics)2) Autocad 3863) Windows 3.0 and 3.1 (Inboard 386/AT model only)